Xingzhi Zhan

activity

20152019

most citedRelation between the number of leaves of a tree and its diameter

1 citations · 1 across the 3 of their papers we have counts for

collaborators

3 papers

math.CO2019★ 1 cited

Relation between the number of leaves of a tree and its diameter

Pu Qiao, Xingzhi Zhan

Let $L (n, d)$ denote the minimum possible number of leaves in a tree of order $n$ and diameter $d .$ In 1975 Lesniak gave the lower bound $B (n, d) = ⌈ 2 (n - 1) / d ⌉$ for $L (n, d) .$ …

math.CO2017

On vertex types of graphs

Pu Qiao, Xingzhi Zhan

The vertices of a graph are classified into seven types by J.T. Hedetniemi, S.M. Hedetniemi, S.T. Hedetniemi and T.M. Lewis and they ask the following questions: 1) What is the sma…

math.CO2015

Nonsymmetric normal entry patterns with the maximum number of distinct indeterminates

Zejun Huang, Xingzhi Zhan

We prove that a nonsymmetric normal entry pattern of order $n$ ( $n \geq 3$ ) has at most $n (n - 3) /2 + 3$ distinct indeterminates and up to permutation similarity this number is attained…